The subject matter disclosed herein relates to methods and corresponding apparatus for resistive spot welding.
Resistive spot welding is commonly understood as a process to couple multiple metal workpieces or sheets by heating the metal sheets. A circuit is created through the metal sheets and a high current is applied thereto, which current interacts with the resistances of the metal sheets to create heat. This heat in turn melts, fuses, or welds the metal sheets together. Resistive spot welding is widely used in various industries that utilize metal workpieces or sheets. For example, resistive spot welding is utilized to manufacture automobiles.
Using certain traditional spot welding technologies and methodologies, welding four or more sheets of sheet metal together may be difficult to achieve with high reliability. Similarly, welding stacks of sheet metal having a stack ratio of seven or higher with these conventional welding technologies and methodologies cannot be achieved with high reliability. Current attempts to use traditional resistive spot welding technologies in such applications have yielded welds that are not suitable for structural use (e.g., to hold panels or pieces together with welds strong enough to, for example, pass crash-test requirements).
There are some high stack ratio welding devices in existence today. However, though suitable for some purposes, such devices do not necessarily meet the needs of all application settings and/or users. For example, these high stack ratio welding devices may be devices utilized specifically and exclusively for such applications. They may require multiple welding tips per side and other various specialized parts and controllers. Such devices, when compared to other traditional equipment such as standard servo-gun style spot welders, are often more expensive and less flexible in their configurations and applications. Thus, an economic and flexible solution is desirable.